At the end of the 4th, or,as some believe, during the middle of the 5th century, Byzantine fortifications were built, serving the purpose of warding off successive raids by the Goths,the Ostrogoths, and later by the Huns.As the 4th century came to an end, it was marked by a bloody slaughter at the Hippodrome with thousands of victims.The Hippodrome was now closed, never to re-open.The affluence and radiance of Thessaloniki of the 5th century was due to the city becoming a centre of trade and commerce, also a centre of administration and a religious centre, a place the Pope staked his claim to.The city boasted a mint and an armoury, it was then that local workshops for sculpture and mosaics flourished.The Rotonda is an excellent example of mosaics.The Acheiropoiitos is the oldest and best preserved church in the East.It is a triple-aisled,royal way Basilica.The early Christian Basilica St.Demetrius, must have been either three-aisled or five-aisled, with a transept or cross-aisle.A famous mosaic of Christ can be seen at the chapel of Osios David. This chapel was formerly the church belonging to the Latomos monastery.